Study Of InSAR Based On Distributed Satellites

Distributed satellites interferometric synthetic aperture radar (DSInSAR) avoids time decorrelation between interfeometric signals and improves the topographic measure sensitivity owing to large baseline formed among satellites. The technique acquiring high precision digital elevation model (DEM) by the system has been hot researching topic in recent years. Compared to conventional InSAR system, DSInSAR system has some new characteristics, such as bistatic radar, squint-model, baseline instability and large baseline and so on. This paper aims to study some key technique caused by these new characteristics.In this paper, the main contents are as follows. (1)Considering new characteristics of DSInSAR system, various error factors are analyzed. Height precision attainable for DSInSAR system is discussed. The radar raw signal simulator is explored. (2)According to the characteristic of large baseline, the criterion of systemic parameters optimization of DSInSAR is proposed. Systemic parameters including look angle, bandwidth and baseline are optimized by the same criterion, and other parameters related to optimal system parameters are determined. (3)Interferometric radar is bistatic and squinted radar in DSInSAR system. Considering to this point, Chirp Scaling imaging algorithm is derived and implemented, which is adapted to bistatic and squinted radar and can perfectly preserve interferometric phase. During the course of algorithm implementation, the effect arose by the baseline instability is eliminated. The simulation results validate the property of phase preserving of bistatic and squinted CS algorithm and the effectiveness of compensated method of baseline instability. (4)Due to large baseline of DSInSAR system, phase unwrapping procedures have difficulty. Multi-baseline data fusion is proposed to reduce or avoid the problem. This method can improve the height precision by shrinking the scope of blind angle and increasing the unambiguous phase range, which is proven by theory and simulation. (5)Rigorous requests for space synchronization and frequency synchronization are presented for acquiring accurate DEM. In order to reduce these rigorous requests, methods of Doppler centroidestimation and phase compensation are proposed in this paper.